It is known in the field of tightness to design apparatus boxes satisfying IP standards, with which an, in particular, damp atmosphere inside the box is rigorously controlled. The IP degrees of protection against the penetration of liquids, and in particular, water, are 0: no protection, 1: drops of water falling vertically cannot penetrate, 2: drops of water falling at a maximum angle of 15° in relation to the vertical cannot penetrate, 3: rain, making a maximum angle of 60° in relation to the vertical cannot penetrate, 4: precipitation in all directions cannot penetrate, 5: water sprayed via a 6.3-mm water gun at a pressure of 0.3 bar cannot penetrate, 6: water sprayed via a 12.5-mm water gun at a pressure of 1 bar cannot penetrate, 7: protection against total immersion at a depth of 1 m, 8: equipment submersible at a great depth.
It turns out, however, that the atmosphere degrades inside the box; thus, an electronic circuit present in the box is affected thereby and ends up breaking down. As it were, the internal electronic circuit, due to its failure, marks the moment when the internal atmosphere in the box was no longer tolerable. Furthermore, it is noted that the phenomenon of degradation may last for a long time, for example, several years, before the manifestation of failure occurs.
The solution held in the state of the art for solving this problem is to reinforce the structures, and typically to place baffles inside the box so that the phenomenon of degradation of atmosphere occurs there as late as possible. This solution is not satisfactory because it leads, sooner or later, to the premature arrival of the failure of the electronic circuit.
In the present invention we proceeded in a different way to solve this problem. An electronic circuit for measuring the state of the atmosphere was included in the box itself. Moreover, this state is sent regularly outside the box to communicate its quality of permanent tightness, or even to lead sufficiently to the repair or changing of the box when the measurement reveals a failure. Thus, one goes from a practice, with which the compliance with packaging procedures was the only element of guaranty of tightness, to a measurement in real time of the state of the internal atmosphere and hence, in particular, of the conditions under which the box was closed and the conditions which it undergoes in its life, such as the changing of type of stresses going, for example, from IP6 to IP7.
It shall be noted that such an interpretation is not immediate insofar as it can be shown with the present invention that a box is thus defective, even if its internal humidity is reduced. In fact, if it is reduced, although the temperature and pressure remain constant, the point is that the tightness therein is not good, and that it is then possible that, under the circumstances, it increases, leading to failure of the circuit.
Furthermore, many electronic monitoring systems (stress recorder) perform a passive monitoring of the environment. The data acquired by these systems are transferred a posteriori or at regular intervals, in particular on a personal computer, for an extensive analysis.